(i) Field of the Invention
This invention relates to hand-held welding torches. More particularly, it relates to a hand-held, self-cooling, gas welding torch using, e.g., propane gas.
(ii) Description of the Prior Art
It is well known that hand-held torches which produce a flame for welding or other purposes become hot. It was proposed in the past to overcome this problem by providing a water-cooled shield around the flame. For example, in the burner taught by Canadian Pat. No. 466,261 issued July 4, 1950 to J. M. Crowe, a water jacket extended throughout the length of the burner body. Also, Canadian Pat. No. 876,526 issued July 27, 1971 to K. Kunioka et al. provided a multi-outlet oxygen fuel blowing lance in which the oxygen blowing pipe was enveloped along its length by cooling water flowing in a cooling mantle.
The provision of air chambers around the burner nozzle has also been suggested. For example, Canadian Pat. No. 954,787 issued Sept. 17, 1974 to W. E. Troyer disclosed a welding gun nozzle in which a fume-extracting chamber was formed concentric with a conventional nozzle. Such chamber had its orifice to designed as to draw in fumes from a region laterally outward from the nozzle. The patented welding gun provided included a nozzle for use in operations where smoke or fumes are created. The first member included a first passageway therethrough. A second member was provided which was coaxial with and surrounded the first member and was spaced radially therefrom along an axis to define a chamber therebetween into which smoke or fumes may be drawn. The second member had an end spaced from the end of the first member along the axis. Means were positioned between the end of the first member and which extended outwardly from the first member a distance substantially equal to the distance of radial spacing of the second member. That means provided a substantially continuous opening forming the sole interconnection from external of the nozzle to the chamber. Means were also provided for connecting the chamber to a source of negative pressure whereby air flow into the opening would remove smoke or fumes from a region laterally outwardly of such opening.
While the patentee did teach that his welding gun also includes means for cooling a welding gun employing the fume-extracting nozzle which allows a welding gun and those hoses used to be made of smaller and lighter material and yet have the long life, such means were not self-operating. The means did require a source of vacuum. While it was stated that, along with the fumes, the nozzle also drew in ambient air in large quantities, and as a result, the nozzle was said actually to operate at cooler temperatures than conventional nozzles, the burning characteristics were not improved.